Blocks per second

[faddat]

Osmo and Gaia are fat, and likely to get fatter fast.

One thing that's very noticeable is as chain state grows, sink speed goes up disproportionately. I propose to change the current block log flying past the screen to an error's only log as well as an indicator showing how many blocks per second are being synced which is refreshed every one or two seconds.

This is part of #413 -- the idea is to first, be able to measure the result of changes with ease instead of the current state of the art:

erm, it took x hours y minutes to get synced, felt faster than yesterday.

[faddat]

I think I know how to do this now